Homes damaged when dam fails in IA

Hundreds of homes damaged as water rushed out of nine-mile-long dam

BY JOHN PAPE |
July 24, 2010

After the dam holding back the nine-mile-long Lake Delhi in northeastern Iowa collapsed in July, the rushing waters of the Maquoketa River severely impacted the residents living directly below the breach. Credit: FEMA/Josh deBerge

Small Business Administration recovery specialist Bill Morris records information during the initial phase of the recovery process from flooding in the Lake Delhi Dam area of northeast Iowa last month. Credit: FEMA/Jace Anderson

After days of torrential rains and a record flood crest on the Maquoketa River, the Delhi Dam in eastern Iowa failed on July 24, sending water crashing into the nearby town of Hopkinton.

Iowa Gov. Chet Culver was in Monticello, one of the threatened communities, and immediately activated the Iowa National Guard to assist in evacuation and rescue operations.

“The rainfall has been massive; there’s been between 9 – 10 inches in the last 12 hours alone, and that was too much pressure on the dam,” Flansburg said.

Delaware County authorities began monitoring the dam closely Saturday morning, warning residents to leave the area as early as daybreak.

At around 1 p.m., water eroded the earthen approach road on the south side of the dam’s center concrete spillway structure, sending water crashing 40 feet down into the downstream portion of the Maquoketa River.

Initially, the water tore a 30-foot-wide hole in the earthen part of the dam. By mid-afternoon Saturday, a second breach had opened, according to Jack Klaus with the Delaware County Office of Emergency Management. Klaus said it was uncertain if any other portions of the dam would fail.

“It’s a very dangerous situation; we’re going to see significant loss of property downstream,” Klaus said.

About half of the 700 residents of the small town of Hopkinton, just downstream from the dam, were evacuated.

Klaus also said the county had run out of barricades to block downstream roads. He said people should stay off any road near the Maquoketa River.

“We can’t guarantee (the roads’) condition or safety at this point,” he said.

Klaus also said more than 500 homes and vacation cabins had been evacuated above the dam because of upstream flooding on the Maquoketa.

Deputy Mike Wilson with the Delaware County Sheriff’s Office said there were no immediate reports of injuries as a result of the dam collapse or flooding.

At the same time, authorities in Jones County were bracing for the water, sandbagging some areas and evacuating others, county emergency management coordinator Brenda Leonard said.

“Right now, we’re in a waiting game to see how much water we’ll get. We’re taking every precaution to protect people living in vulnerable areas,” Leonard said. “We’ve got the state patrol in the air monitoring (the crest) as it heads our way.”

Leonard said an estimated 70 – 100 homes in Monticello, a town of about 3,600 residents 30 miles downstream from the dam, were evacuated.

Also evacuated was the Jones County Fairgrounds where the annual country fair was underway. The fairgrounds are adjacent to the Maquoketa River in Monticello.

“They’ve cancelled the concert and all fair activities,” Leonard said. “We’ve had reports of structures swept away and large trees and boats being carried downstream by the floodwaters. We’re not taking any chances.”

Further downstream, Jackson County Emergency Management Coordinator Lyn Medinger said residents in the town of Maquoketa were bracing for flooding in areas near the river that gave the city its name.

“We’re expecting the river to hit 38 feet. That’s higher than our last big flood in 2002,” Medinger said. “Anyone that flooded in 2002 will most likely get flooded again.”

Medinger also said volunteers were filling sandbags to protect the city’s electric company, public works department and wastewater treatment plant, all of which are in the flood-prone area of the town.

“We’re out there doing our best to protect those facilities,” he said.

Luckily, most of the city is outside of the flood-prone zone and only homes in low-lying areas are expected to see flood water.

National Weather Service spokesperson Donna Dubberke warned downstream residents to brace for two separate flood crests.

“There will be the initial crest from the dam failure, then we’re forecasting a secondary crest because of the flood water that was still upstream,” Dubberke said.

The Delhi Dam was originally built in the 1920s as a hydroelectric dam. While the dam was no longer used to generate electricity, Lake Delhi continued to be a popular recreational lake lined with homes and cabins.

The Delhi Dam was last inspected by the Iowa Department of Natural Resources in May of 2009. No major structural problems were found at that time.

The 140-mile-long Maquoketa River rises in Fayette County in northeast Iowa, and travels through Clayton, Delaware, Jones and Jackson Counties before emptying into the Mississippi River about 30 miles southeast of Dubuque.

Iowa’s flooding problems were not limited to areas along the Maquoketa River. Days of torrential rain also forced city officials in the city of Independence to close streets near the downtown area after the Wapsipinicon River rose to 10 feet above flood stage following 14 inches of rainfall in a 36-hour period. The city also closed a major bridge over the river as floodwaters lapped just beneath the structure.

Buchanan County Emergency Management Coordinator Rick Wulfekuhle said the area took a “direct hit” from severe thunderstorms.

Flood warnings also were issued for Bremer and northern Black Hawk counties after secondary roads were flooded due to the heavy rains.

The National Weather Service said 6-10 inches of rain has fallen over northeastern Iowa in the past three days.

The storm system, however, brought other severe weather to the state. A tornado touched down Friday near the south central Iowa community of Indianola, causing minor property damage but no injuries.

On Friday, Gov. Culver extended disaster proclamations for 31 Iowa counties because of the flooding and severe weather the state has experienced over recent weeks.